University of Delaware

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• University of Delaware
• December 10, 2007
• Senior Design Team 15
• Anthony Brazen IV
• Nick Hirannet
• Sam Holland
• Megan Keenan

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• To improve the robustness and reliability of the
  tablet feeding process.
• This can be done through prevention and detection

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• The tablets are moved along the tracks with the
  aid of a linear vibrator creating backpressure

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• The tablets drop through the holes and chutes
  into the flex
• Sensors are currently placed at the top of the
  chute to detect that a tablet has fallen

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• What?
• A flex does not receive a tablet
• Entire lot must be opened and inspected
• Happens 45 out of 8 million tablet drops

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• Why?
• Tablet breaks top sensor and may get stuck in the
  chute
• Tablet bounces off side walls causing delayed
  drop
• Tablet never exits the chute
• Possibility for erroneous test result
• Loss of time and money due to product
  re-inspection
• Hand inspection is currently used to ensure that
  the correct amount of tablets are in each flex
• Expensive
• Time consuming

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• The tablets exit the chute at a 90 degree angle
  from entrance into chute
• The drastic turn could cause the tablet to hit
  the side walls, delaying exit from the chute

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• Top 10 Wants

Constraints
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Prevention
Detection
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• Too many modifications to the chute would cause
  Siemens to redesign the entire process
• Too expensive and time consuming
• New Feature Add sensors to the bottom of the
  chute
• Sensor detection in current process is placed at
  the top, which provides knowledge of the tablet
  entry, but problem arises upon tablet exit

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• Holes will be drilled into the sides of the
  chutes and the lowest point where the chutes and
  Lexan meet
• Twelve sets of visual sensors will be attached to
  the bottom surface of the Lexan guard
• Will utilize same communication software that
  Siemens currently uses

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• Met with Keyence Sales Rep.
• 4 sensors were ordered
• Two were able to be eliminated immediately based
  on visual inspection
• FU-12 and FU-51TZ
• The FU-50 and FU-59 were tested

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• Test station set-up

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• FU-50 worked well for large tablets, but was
  quickly eliminated after missing several small
  tablets in the first two trials
• Due to large beam aperture, which causes a
  decrease in sensitivity

Diameter of ALL tablets 0.2185 in. Large tablet
height 0.1510 in. Small tablet height 0.0835
in. Red Strength of beam Green Threshold
setting
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• 2000 tablets were dropped
• Eight trials of 250 tablets were tested
• ALL tablets were detected

SMALL Tablets
LARGE Tablets
Diameter of ALL tablets 0.2185 in. Large tablet
height 0.1510 in. Small tablet height 0.0835
in. Red Strength of beam Green Threshold
setting
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Diameter of ALL tablets 0.2185 in. Large tablet
height 0.1510 in. Small tablet height 0.0835
in. Red Strength of beam Green Threshold
setting
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• 4 modes of failure for detection have been
  identified
• 2 create undesirable risk levels
• Sensor gets blocked by an object
• Sensor becomes unaligned
• Both potential effects are that sensor detects a
  non-existent tablet
• HMI and PLC controls will identify a blocked beam
  or misalignment

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• Cutting an existing tablet track and adding a
  90 turn
• Desired chute drops tablets straight down
• Eliminates current chute

• 2 ways to achieve this
• 2- 45 straight angle turn
• Curved radius turn

Current State
Desired State
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• 2 aluminum tracks were milled
• Tracks were mounted on linear vibrator
• Test to determine what prototype allows
• Tablets to reach the end of the track
• Tablets get to end of track fastest

Vibration
Vibration
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• Tracks without flipper mechanism

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• Radius Track has ability to move tablets faster
• Current system rate 1.1 tablets/sec
• Both new designs exceed this rate
• Angle track moved Large tablets faster

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• If Siemens decides to replace their current
  tracks with our 45 degree turned tracks
• May not allow required space for vacuum mechanism
• Alternative to vacuum flipper mechanism

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• Full circle rotation

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• Half rotation

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• Aluminum cylindrical flipper placed at end of
  track
• Six slots cut along the cylinder to receive
  tablets from track
• Upon loading, cylinder will rotate CW allowing
  tablets to be released

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• Cost Justification 1 bad flex 25,000 in lost
  productivity, re-packaging,
• and labor
• 10 bad lots per year 250,000
• Detection at the bottom of chute pays for itself

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Tracks
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• 0 defects in a sample of 250 tablets is
  considered acceptable by Siemens statistical
  analysis
• We tested 8 samples of 250 tablets to validate
  this acceptance

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• The number of samples (n) to be taken can be
  calculated by the following expression
• Z(A) standard normal variant value for ? error
• Z(B) standard normal variant value for ß error
• AQL (Average Quality Level)
• LTPD (Lot Tolerance Percent Defective)

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• The acceptance number (c) (number of defects
  per sample permitted) can be determined by the
  following expression
• ? Producers Risk
• ? Consumers Risk
• AQL (Average Quality Level)
• LTPD (Lot Tolerance Percent Defective)
• n Required Sample Size
• c Acceptance Number (Number of Defects
  Permitted in Sample)

c
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